Soybean Use Poultry FACT SHEET MEAL

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1 Soybean Use Poultry Park W. Waldroup, Department of Poultry Science, University of Arkansas Dr. Keith Smith, Keith Smith and Associates

2 Soybean Meal in Poultry Nutrition Soybean Meal is Ideal Protein for Poultry Soybean meal dominates the market for protein supplements for poultry. There are a number of reasons for this, including its consistency in nutrient content, its ready availability year-round, and its high content of crude protein. Because poultry producers desire high-energy diets, soybean meal is a superior value because no other common plant protein feedstuff exceeds soybean meal in crude protein content. Soybean meal matches or exceeds all other common plant proteins in both total and digestible amino acid content (Table 1). Soybean meal is perhaps the only common protein supplement that is typically included in poultry rations with no limitation as to the quantity used. When properly toasted to denature the trypsin inhibitors, there are no anti-nutritive factors to consider when formulating diets. With the single exception of methionine, soybean meal is an almost ideal protein supplement for all types of poultry. When blended with corn or grain sorghum, soybean meal provides a good balance of all the essential amino acids needed by poultry except for methionine. However, methionine is economically provided by supplements produced by the chemical industry, allowing simple corn-soybean meal diets to effectively meet the amino acid requirements of the chick. History of Usage in Poultry Diets Given the overwhelming use of soybean meal in poultry feeds today, it is difficult to imagine that not much more than 50 years ago soybean meal was not the predominant protein source. In the early 1940s, manufacture of poultry feed was dominated by large flour millers, who used poultry feed as an outlet for wheat bran and other milling byproducts. Animal feedstuffs such as meat and bone meal and fish meal were favored as protein sources, not only for the protein they provided but also because they were rich sources of vitamins and minerals. The onset of World War II caused an increased demand for meat production, but the supply of imported meat proteins was limited. This focused attention on soybean meal as a potential protein supplement. Development of processes to toast the soybean meal to denature trypsin inhibitors, along with development of systems to produce vitamins by chemical synthesis and fermentation, allowed for the rapid increase in the demand for soybean meal. The final factor that allowed for greater use of soybean meal was the discovery of vitamin B12 in This ended the necessity for the inclusion of animal protein sources in feeds for monogastric animals. Soybean Meal and the Integrated Broiler Industry The development of the integrated system of poultry production began in the 1950s when progressive individuals set up systems where they controlled the production of poultry from hatchery, feed manufacturing and processing. As poultry entrepreneurs established their own feed mills, they had no ties to the use of milling byproducts and sought the least expensive and most reliable sources of protein. The development of the linear programming system of feed formulation in the mid 1960s gave further impetus to increased use of soybean meal. As nutritionists began to use the computer to formulate feeds, they quickly found that simple diets based on corn, soybean meal, a methionine supplement, vitamins and minerals were not only effective but also the least-cost way to produce chickens. The rapid rise in poultry consumption (Table 2) has created an even greater demand for soybean meal, both in the United States and in other developing countries. Soybean Meal Usage by the Poulrty Industry The poultry industry, including broilers, turkeys and laying hens, is the major user of soybean meal in the United States. Broilers and turkeys consume about 44 percent of all the soybeans used by livestock in the United States, with layers consuming an additional 7 percent, for a total of 51 percent (Table 3). Soybean meal is by far the dominant plant protein produced in the United States (Table 4). Few of the other plant proteins such as cottonseed meal or sunflower meal are used by the poultry industry. It is estimated that more than 98 percent of the plant protein used in poultry feeds is from soybean meal, with more than 66 percent of all the protein in poultry diets provided from soybean meal. Broilers have a high demand for crude protein and amino acids (Table 5), and thus need a protein source high in amino acids. Results from a recent industry survey indicate that typical amounts of soybean meal added are 29.4 percent in starter feeds, 23.8 percent in grower feeds and 17.8 percent in finisher diets. Declining Usage of Meat Byproducts in Poultry Feed Because of consumer concerns about the health and safety of animals fed rendered meat byproducts, coupled with the desire to reduce excessive phosphorus in poultry excreta, the amount of supplemental meat products in poultry feeds has dropped rapidly in the last two years. A recent agricultural survey indicated that animal proteins were added at less than 3 percent in poultry feeds, compared with about 5 percent in previous years. This will place further demands upon soybean meal as a protein source for poultry. Proper Processing Necessary Soybeans must be heat-processed to denature the various protease inhibitors, the chief of which are the trypsin inhibitors. Both over processing, which ties up essential amino acids 2

3 (especially lysine), and under processing are considered detrimental to the effective usage of soybean meal. The urease test, which measures the rise in ph when soybean meal is placed in a solution containing urea, is the most widely used method to monitor proper toasting of soybean meal for animal feed. Although there is no official urease level specified for poultry, the general recommendation is that the urease be less than 0.20 ph rise; however, recent studies have shown that as much as 0.50 ph rise is acceptable. Because the urease test does not detect over processing, it is desirable to have some residual urease activity (0.01 to 0.05 units). Over processing is best determined by measuring protein solubility in a KOH solution. It is suggested that KOH solubility in excess of 85 percent or less than 70 percent indicates under- or overprocessing of the meal. However, studies are not consistent in this respect. Particle size of the meal plays a great role in the consistency of responses to the KOH solubility test. Improving Nutritive Value Through Plant Breeding As in many crops, the primary focus of plant breeders has been on increased yield or better resistance to disease. However, more attention is being focused today on improving nutritive value. Most of the focus has been on improving the methionine content, reducing the phytate-bound phosphorus, and reducing the oligosaccharide content. Although the deficiency of methionine is often mentioned as a detriment to the use of soybean meal in poultry feeds, it is readily and economically produced by chemical synthesis, using toxic byproducts of the chemical industry to produce a desirable and economical feed supplement. Although plant breeders have expressed a desire to increase the methionine content of soybeans, it is not a high priority due to the economy of providing methionine in supplemental form. Much of the phosphorus in soybeans is present in a complex, with phytic acid rendering the phosphorus in a poorly digested form for monogastric animals. Phosphorus is one of the most expensive nutrients in a poultry diet, and livestock producers everywhere are becoming more concerned about the effects of phosphorus in the manure upon eutrophication of surface waters. Although commercial phytase supplements are available, their cost presently is greater than the amount of phosphorus they release. Genetic soybean mutants have been found with a lower percentage of their phosphorus bound in the phytate form. To date, however, the productivity of low phytate soybeans has been poor. Soybean meal contains one of the highest levels of phosphorus of all plant proteins, so genetic improvements in this area would be highly beneficial to the poultry industry. The other major factor that should be addressed by either selective breeding or by modifications in processing procedures is the soybean carbohydrate. Much of the carbohydrate in soybeans is present as the oligosaccharides known as raffinose and stachyose. These require the enzyme alpha-galactosidase that is absent in poultry. Because carbohydrates constitute approximately 35 percent of the soybean meal, the presence of these poorly digestible carbohydrates minimizes the amount of metabolizable energy the chick can derive from the meal. In addition, the excreted carbohydrates are very sticky, leading to a wet, sticky litter that may adhere to the bottom of the feet and possibly lead to leg disorders. These may be removed from the soybean meal by ethanol extraction, as done in the production of high-protein soy isolates. As it is unlikely that the soybean processing industry will markedly modify its processing procedures, breeding programs that concentrate on reducing oligosaccharides in the seed may be the most desirable route. 3

4 Table 1 Typical Nutrient Composition of Commonly Used Plant Protein Sources for Poultry AS-FED BASIS SOYBEAN 44 SOYBEAN 46 SOYBEAN 48 SUNFLOWER 34 RAPESEED 00 PEANUT SESAME COTTONSEED SAFLOWER Dry Matter % Crude Protein % Crude Fat % Crude Fiber % ME, kcal/g TOTAL AMINO ACIDS (%) Lys Met Cys Thr Trp Arg Gly Ser His Ile Leu Phe Val DIGESTIBLE AMINO ACIDS (%) Lys Met Cys Thr Trp n.a. n.a Arg Gly Ser His Ile Leu Phe Val

5 Table 2 U.S. Meat Consumption (Pounds Per Capita) RED MEAT Beef Veal Pork Lamb Chicken Turkey FISH AND SHELLFISH Fish and Shellfish Source: USDA and National Marine Fisheries Service Table 3 Utilization of Soybean Meal by Livestock in the United States SPECIES MILLION METRIC TONS PERCENT OF TOTAL Poultry Swine Beef Eggs Dairy Pet Foods Aquaculture Other TOTAL *Source: United Soybean Board 1999/2000 5

6 Table 4 Production of Processed Protein Sources and Byproducts in the U.S. (1,000 Metric Tons) Table 5 Protein and Amino Acid Requirements of Broiler Chickens 1 FEED NUTRIENT UNIT 0-3 WEEKS 3-6 WEEKS 6-8 WEEKS HIGH PROTEIN OILSEED S Soybean Cottonseed Linseed Metabolizable energy 2 Kcal/kg Crude protein 3 % Arginine % Peanut Sunflower Canola Total oilseed meals Glycine + Serine % 1.25 Histidine % 0.35 Isoleucine % ANIMAL PROTEIN Tankage and meat meal Fish meal and solubles Milk products Total animal proteins GRAIN PROTEIN FEEDS Gluten feed and meal OTHER Wheat millfeeds Rice millfeeds Alfalafa meal Fats and oils Leucine % Lysine % Methionine % Methionine + Cystine % Phenylalanine % Phenylalanine + Tyrosine % Proline % Threonine % Tryptophan % Miscellaneous byproduct feeds Valine % Total other GRAND TOTAL *Source: Feedstuffs Reference Issue, July 30, Source: National Research Council, These are typical energy concentrations. Different energy values may be appropriate depending upon local ingredient prices and availability. 3 Broiler chickens do not have a requirement for crude protein per se. However, there should be sufficient crude protein to ensure an adequate nitrogen supply for synthesis of dietary dispensable amino acids. Suggested requirements for crude protein are typical of those derived with corn and soybean meal-based diets, and levels can be reduced when synthetic amino acids are fed. Conclusions Soybean meal is and will continue to be the preferred protein supplement for poultry feeds. With the probable decline in the use of animal byproducts, even more soybean meal will be used. Genetic improvements in reducing the phytate-bound phosphorus, and reduction or elimination of oligosaccharide carbohydrates are the most important economical traits that should be addressed. Key sponsors for this information include the Iowa, Illinois, Indiana, Kentucky, Michigan, Minnesota and Nebraska Soybean Boards. For more information or to submit questions, please visit 6